We propose to prepare and study antisera to various lymphokines. A multispecific antiserum against several mediators in supernatants of activated lymphocyte cultures has already been described by us. We will continue to explore its range of in vitro and in vivo biologic activity, and in addition, will attempt the production of monospecific antisera with restricted specificity to a single lymphokine such as migration inhibition factor or macrophage chemotactic factor. These reagents will be used for isolation and purification of various mediators, detection of their production by lymphocytes, and studies of their interaction with target cells. We have already shown that the anti-lymphokine antiserum is capable of suppressing delayed hypersensitivity reactions, and we will explore similar effects in other in vivo manifestations of cell-mediated immunity in order to determine the range of situations in which this novel mode of immunosuppression can be effective. These studies will be performed in order to characterize a form of immunologic intervention which could have application in man.